1. Field of the Invention
The invention concerns an object with a matted surface, with a substrate on which a plastic layer, made of a polymerized organic material with a structured surface that appears optically mat, is applied. Furthermore, the invention concerns a polymerization method for the production of a matted surface on a substrate.
2. Discussion of the Background
A method is known for producing matted surfaces on objects such as paper, wood, or plastic sheetings, by providing the substrate material with a matting lacquer that can be cured by UV light or by means of electron beams. Such matting lacquers contain matting agents that serve to produce the matting. SiO.sub.2 particles dispersed in the lacquer are common as matting agents.
The matted surface of the objects is produced in the known polymerization methods by applying a film of the lacquer on a substrate and subsequently polymerizing by radiation with a wavelength in the ultraviolet range or by electron beams. Upon curing the lacquer film, the dispersed matting agents produce a slight unevenness of the free surface, which therefore appears optically mat.
The matting agents dispersed in the lacquer reflect the UV radiation or the electron beams, and therefore hinder the thorough polymerization of the lacquer film, in particular with high concentrations of matting agents. The known matting lacquer layers can therefore exhibit a poor drying or polymerization behavior.
Frequently, polymerization-promoting additives, such as photoinitiators, are admixed to the lacquer to accelerate curing. These additives are frequently health hazards. It may also occur that the lacquer layers are cured only in part and that substances harmful to people's health are released from the areas that were not thoroughly cured.
In the known polymerization methods, it is necessary to produce a homogeneous distribution of the additives in the lacquer, in particular, the dispersed matting agents, before the application of the lacquer layers, and to maintain the matting agents on the substrate during the application of the lacquer film. It has become evident, however, that the matting agents are deposited during certain steps of the method upon application of the lacquer film. Thus, for example, upon applying colored lacquers by means of rollers on the substrate, the matting agents accumulate on the rollers, wherein lacquer layers may form with nonhomogeneous distribution of the matting agents.